A Hillsborough County sheriff's deputy and an off-duty Hillsborough reserve firefighter rescued the semitrailer's driver, Jeffery Scott Cook, 29, of St. Augustine.

Cook, of St. Augustine, was taken to Tampa General Hospital with serious injuries, authorities said. He was reported to be in stable condition, officials said.

The vehicle was removed from the riverbank and the roadway was reopened as of 4:40 p.m., the Florida Highway Patrol said.

Cook was traveling south on I-75 north of the Alafia in the outside center lane about 12:30 p.m., troopers said. For unknown reasons, he lost control of the rig, which collided with the inside barrier wall, overturned and fell from the bridge, troopers said.

The truck, trailer and bulldozer landed on the north shoreline of the river, troopers said.

The 2001 International tractor-trailer was operated by M.D. Towing Inc. of Jacksonville, troopers said.